Artificial silk and the process of producing the same



Patented Mar. 17, 1931' UNITED STATES PATENT osrlcs :Bmmo BORZYKOWSKI, OF PAfiIS FRANCE, ASSIGNOR TO SWISS BOBVISK OOMPANY,

OF WILMINGTON, DELAWARE, A CORPORATION OF DELAWARE ARTIFICIAL SILK AND THE PROCESS OF PRODUCING THE SAME 1T0 Drawing. Application filed September 27, 1926, Serial No. 138,122, and in Germany November 11, 1925.

In the artificial silk industry particularly at the beginning of this branch of the art, great importance was attached to the production of fibres having a very brilliant lustre. During the course of time, however, as the field of use of artificial silk greatly increased, a demand arose for fibres not having this very brilliant lustre, but having a duller, or silk-like aspect. Many proposals have been made for securing this result.

I have now found it possible to produce utilizable dull finish fibres with asilk-like lustre by producing the fibres in known manner from viscose, but with a subsequent treatment which forms the essential feature of the, present invention.

The setting of the thread from the viscose solution can be effected-in known.manner, by the use of any of the commonly used setting baths. The viscose used can be of any age (or stage of ripeness), or can be fresh (1. e. directly after its original preparation). As is known, in the said operation a art of the sulfur is set free, during the setting operation, in a very finely divided state, perhaps colloidal, on the surface of (and to some extent within) the threads or filaments. This ma exist as elemental sulfur, or as precipitate sulfur-containing byproducts, in-

30 soluble in water but existing in a very finely v divided state.

In my process, the silk is not, as is usually done, desulfurized before the bleaching, but (after washin out soluble acids and salts, if

86 desired) may e bleached directly with the adherent sulfur. The result thereof is that colloidal precipitates or deposits are formed which are not removed or are only partially removed, during-subsequent washing.

The dull, silk-like appearance of the fibre obtained in this manner is permanent and does not disappear even when the artificialsilk is dyed.

The action of the adhering salts for the to formation of colloidal precipltations or deositions, on or in the silk fibres, may be her increased by passage of the raw artificial silk through a suitable salt solution before the reviving '(scrooping, or toning), op-

. eration.

' preferably EwampZe.-Viscose silk prepared inthc usual or any a proved manner, but without being subjecte to the usual desulfurizing operation, is subjected to the usual washing and twisting, is preferably formed into hanks or skeins and then, as so-called raw silk, it may be introdced directly (that is, without being a bleaching bath containing, for example, 0.01 to 0.15% .of free chlorine. The bleaching may be performed with other bleaching agents that do not dissolve elemental sulfur, e. g. H 0 or numerous others. In some cases, as where the silk is to be (1 ed a dark color, the bleaching operation may e omitted. It is then passed (if it has been treated with chlorine) into an acid bath, to which aluminum, ma esium, zinc or other similar salts (say sul ates or chlorides) may be added. The salts of these metals are of especial interest because the salts themselves and any insoluble com ounds thereof, formed in the process, are w its, and hence do not discolor the silk. The amount of salts is (in said bath, or a siparate bath if acid is not used) om 1 to 2% with respect to the bath. As is known, one effect of the salts in this bath, is to prevent excessive action of the acid of this bath upon the silk, and in the present instance the salts in this bath react with the undesulfurized fibre to form white colloidal precipitations upon or in the silk fibres. K The silk is then treated in the usual toning (scroo in bath (say soap solution) until the silk sfiein just shows a. weakly acld reaction.

I claim; 1. In the production of dull fimsh viscose silk, the herein described improvement of treating the viscose silk, while still containand thereafter toning (scrooping) inthe preliminarily desulfurized), into recess of producing artificial silk usual manner all without subjecting said silk to a desuliurizing treatment.

3. Finished viscose silk retaining its original substantially colloidall preci ltated sulfur and having a white ,eart met com ound preciptated in a substantially colloid state on and in its fibres the same having a'dull silk-like lustre which is persistent even after dyeing. 4. process which comprises forming upon the fibres of undesulfurlzed viscose silk,

a very finely divided precipitate, from a soluble earth-metal salt, to thereby give a dull silk-like effect to the product.

5. Bleached viscose silk retaining its origi nal colloidall precipitated sulphur, in a substantially co oidal state, on and in its fibres, the same having a dull silk-like lustre which is ersistent even after dyeing. A testimony whereof I have signed my name to this s ecification.

B NNO BORZYKOWSKI. 

